How to Get WordPress 4.4 alpha and Beta

This was posted on October 2, 2015: https://make.wordpress.org/core/2015/10/02/update-on-twenty-sixteen/ and within the text is the following quote: “Twenty Sixteen now also will require 4.4-alpha”.

The release date for WordPress 4.4 is targeted for December 8, 2015:
https://make.wordpress.org/core/version-4-4-project-schedule/

The only way you can upgrade your website to WordPress 4.4 alpha is by using this Plugin: https://wordpress.org/plugins/wordpress-beta-tester/. You have to install it, enable it, and then choose option #2 (Bleeding edge nightlies) on its Settings page.

If you have never done that before, I would very carefully read both the Reviews and Support Tabs for that plugin. Otherwise, you’ll have to wait until WordPress 4.4 comes out in the first week of December to download the finished product of Twenty Sixteen.

Hope that helps.